Contents

Chapter Description

This chapter helps you prepare for the CCNP ROUTE exam by covering the following topics related to implementing path control: Offset lists, Cisco IOS IP Service Level Agreements, and Policy routing using route maps. It also uses route maps as a Configuration example.

From the Book

This chapter provides information concerning the following topics related to implementing path control:

Offset lists

Cisco IOS IP Service Level Agreements

Policy routing using route maps

Configuration example: route maps

NOTE

Path control is the mechanism that changes default packet forwarding across a network. It is not quality of service (QoS) or MPLS Traffic Engineering (MPLS-TE). Path control is a collection of tools or a set of commands that is able to manipulate the routing protocol forwarding table or to bypass default packet forwarding. The manipulation of routing information may be required to obtain better resiliency, performance, or availability in your network.

There are other filters or tools available to assist in the manipulation of the routing table. These include

Route maps

Prefix lists

Distribute lists

Administrative distance

Route tagging

These are mostly protocol dependent and have been covered in other chapters in this book.

Offset Lists

NOTE

The offset-list command is only applicable to EIGRP and RIP routing protocols. The offset-list command is used to add an offset to incoming and outgoing metrics to routes learned using these protocols. The offset value is added to the metric.

TIP

An offset list with an interface type and number is considered to be extended and will take precedence over an offset list that is not extended. This means that if an entry passes the extended offset list and the normal offset list, the offset of the extended offset list is added to the metric.

Router(config)#router eigrp 11

Enables EIGRP routing process with an autonomous system number of 11.

Router(config-router)#offset-list 21 out 10

Applies an offset list of 10 to the delay component (outgoing metrics) of a router to networks matching ACL 21.

Router(config-router)#offset-list 21 in 10 fastethernet 0/0

Applies an offset list of 10 to the incoming metrics of routes matching ACL 21 learned from interface FastEthernet 0/0.